DBA技術分享(二)-MYSQL常用查詢Columns和Views
阿新 • • 發佈:2022-05-29
概述
分享一下工作中常見的mysql指令碼,此次分享的內容如下:
- Columns
- Views
一、Columns
1.1 列出 MySQL 資料庫中的表列
select tab.table_schema as database_schema,
tab.table_name as table_name,
col.ordinal_position as column_id,
col.column_name as column_name,
col.data_type as data_type,
case when col.numeric_precision is not null
then col.numeric_precision
else col.character_maximum_length end as max_length,
case when col.datetime_precision is not null
then col.datetime_precision
when col.numeric_scale is not null
then col.numeric_scale
else 0 end as 'precision'
from information_schema.tables as tab
inner join information_schema.columns as col
on col.table_schema = tab.table_schema
and col.table_name = tab.table_name
where tab.table_type = 'BASE TABLE'
and tab.table_schema not in ('information_schema','mysql',
'performance_schema','sys')
-- uncomment line below for current database only
-- and tab.table_schema = database()
-- uncomment line below and provide specific database name
-- and tab.table_schema = 'your_database_name'
order by tab.table_name,
col.ordinal_position;
注意:要檢視特定資料庫中的列,請取消註釋上述子句之一。
說明:
- schema_name - 資料庫名稱
- table_name - 表名
- column_id - 表列 id,每個表從 1 開始
- column_name - 列的名稱
- data_type - 列資料型別
- max_length - 資料型別最大長度
- precision- 資料型別精度
1.2 列出 MySQL 資料庫中特定表中的所有列
select ordinal_position as column_id,
column_name as column_name,
data_type as data_type,
case when numeric_precision is not null
then numeric_precision
else character_maximum_length end as max_length,
case when datetime_precision is not null
then datetime_precision
when numeric_scale is not null
then numeric_scale
else 0 end as data_precision,
is_nullable,
column_default
from information_schema.columns
where table_name = 'table name' -- put table name here
-- and table_schema = 'schema name' -- put schema name here
order by ordinal_position;
說明:
- column_id - 表中的列位置,從 1 開始
- column_name - 表中列的名稱
- data_type - 列資料型別
- max_length - 資料型別最大長度
- data_precision - 資料型別精度
- is_nullable - 如果列可以為空,則為 YES,否則為 NO
- column_default - 列的預設表示式
1.3 列出 MySQL 資料庫中所有包含詳細資訊的表列(PKs、UKs、FKs、Default、Computed 等)
select col.table_schema as database_name,
col.table_name,
col.column_name,
col.data_type,
case when col.data_type in ('datetime', 'timestamp', 'time')
then col.datetime_precision
else col.numeric_precision end as 'precision',
col.numeric_scale,
col.character_maximum_length as char_length,
col.column_default,
col.generation_expression,
case when (group_concat(constraint_type separator ', '))
like '%PRIMARY KEY%'
then 'YES' else 'NO' end as PK,
case when (group_concat(constraint_type separator ', '))
like '%UNIQUE%'
then 'YES' else 'NO' end as UQ,
case when (group_concat(constraint_type separator ', '))
like '%FOREIGN KEY%'
then 'YES' else 'NO' end as FK,
col.is_nullable
from information_schema.columns col
join information_schema.tables tab
on col.table_schema = tab.table_schema
and col.table_name = tab.table_name
and tab.table_type = 'BASE TABLE'
left join information_schema.key_column_usage kcu
on col.table_schema = kcu.table_schema
and col.table_name = kcu.table_name
and col.column_name = kcu.column_name
left join information_schema.table_constraints tco
on kcu.constraint_schema = tco.constraint_schema
and kcu.constraint_name = tco.constraint_name
and kcu.table_name = tco.table_name
where col.table_schema not in('information_schema', 'sys',
'performance_schema', 'mysql')
group by 1,2,3,4,5,6,7,8,9,13
order by col.table_schema,
col.table_name,
col.column_name;
說明:
- database_name - 資料庫(模式)名稱
- table_name - 表名
- column_name - 列名
- data_type - 資料列的型別包含
- 精度- 數字型別的精度或日期時間型別的小數位數
- numeric_scale - 數字資料型別的比例
- char_length - 最大字元長度
- column_default - 列的預設值
- PK - 指示列是否為主鍵
- FK - 指示列是否為外來鍵
- UQ - 指示列是否必須在表中具有唯一值
- is_nullable - 指示列是否可以為空
1.4 列出 MySQL 資料庫中所有計算(生成)的列
select table_schema as database_name,
table_name,
column_name,
data_type,
generation_expression
from information_schema.columns
where length(generation_expression) > 0
and table_schema not in ('information_schema', 'sys',
'performance_schema', 'mysql')
order by table_schema,
table_name,
column_name;
說明:
- database_name - 包含表的資料庫(模式)名稱
- table_name - 表名
- column_name - 列的名稱
- data_type - 列的資料型別
- generation_expression - 計算公式
二、Views
2.1 列出 MySQL 資料庫中的檢視
select table_schema as database_name,
table_name as view_name
from information_schema.views
where table_schema not in ('sys','information_schema',
'mysql', 'performance_schema')
-- and table_schema = 'database_name' -- put your database name here
order by table_schema,
table_name;
說明:
- database_name - 包含檢視的資料庫(模式)的名稱
- view_name - 檢視名稱
2.2 列出 MySQL 中的檢視及其定義
select vw.table_schema as database_name,
vw.table_name as view_name,
vw.view_definition as definition,
tb.table_comment as description
from information_schema.views as vw
inner join information_schema.tables as tb
on tb.table_name = vw.table_name
-- where vw.table_schema = 'your database name'
order by database_name, view_name;
注意:如果您需要特定資料庫(模式)的資訊,請取消註釋 table_schema 行並提供您的資料庫名稱。
說明:
- schema_name - 檢視的資料庫(模式)名稱
- view_name - 檢視的名稱
- 定義- 檢視的定義指令碼
- 描述- 檢視的描述
2.3 列出 MySQL 資料庫中的檢視中的所有列
select col.table_schema as database_name,
col.table_name as view_name,
col.ordinal_position,
col.column_name,
col.data_type,
case when col.character_maximum_length is not null
then col.character_maximum_length
else col.numeric_precision end as max_length,
col.is_nullable
from information_schema.columns col
join information_schema.views vie on vie.table_schema = col.table_schema
and vie.table_name = col.table_name
where col.table_schema not in ('sys','information_schema',
'mysql', 'performance_schema')
-- and vie.table_schema = 'database_name' -- put your database name here
order by col.table_schema,
col.table_name,
col.ordinal_position;
說明:
- database_name - 資料庫(模式)名稱
- view_name - 檢視名稱
- column_name - 列名
- data_type - 列資料型別
- max_length
- - 列長度:
- 對於字串列,以字元為單位的最大長度。
- 對於數值列,數值精度。
- is_nullable - 指示列是否允許空值的標誌
2.4 列出 MySQL 資料庫中檢視使用的表
查詢在8.0.13 MySQL 版本下執行。
select vtu.view_schema as database_name,
vtu.view_name as view_name,
vtu.table_schema as referenced_database_name,
vtu.table_name as referenced_object_name,
tab.table_type as object_type
from information_schema.view_table_usage vtu
join information_schema.tables tab on vtu.table_schema = tab.table_schema
and vtu.table_name = tab.table_name
where view_schema not in ('sys','information_schema',
'mysql', 'performance_schema')
-- and tab.table_schema = 'database_name' -- put your database name here
order by vtu.view_schema,
vtu.view_name;
說明:
- database_name - 檢視資料庫(模式)名稱
- view_name - 檢視名稱
- referenced_database_name - 檢視引用的表資料庫名稱
- referenced_object_name - 檢視引用的表名
- object_type
- - 引用物件的型別:
- BASE TABLE
- VIEW